As aging of the skin progresses, changes take place, particularly at the epidermal and dermal levels. Within the epidermis, the production of new cells no longer compensates for desquamation, and the epidermis gradually gets thinner. The sebaceous glands become functionally less active and the skin becomes dry.
At the level of the dermis, the formation of new collagen, responsible for skin tone, is slowed by reduction of the secretive activity of the fibroblasts. Intermolecular crosslinks within the collagen fibers multiply, bringing about structural rigidity, reduction in the capacity to absorb water, and reduction in the supply of nutrients and oxygen.
These harmful transformations cause a loss of elasticity, as well as dehydration, asphyxiation, and dryness of the skin. These phenomena produce wrinkles, notably on the face where the skin is under particular attack by external factors (e.g. bad weather, pollution, light radiation) and by internal factors (illnesses, increase in age, etc).
Cosmetic preparations intended to combat aging of the skin already exist on the market. These known preparations contain many varied compounds, such as biologicals (for example placenta extracts), collagen, polyvitamin mixtures, and essential fatty acids. Cosmetic compositions containing fetal calf serum, extracts from organs such as the thymus or spleen, and animal extracts are also known, described for example in French Patent Application 84 19446.
However the use in beauty care of the real topical properties of ribosomes has never before been described, and ribosomes extracted from vegetable and animal cells, or from the cells of microorganisms, have never before been used to combat aging of the skin. Ribosomes are the sub-cellular organelles composed of RNA and proteins involved in the synthesis of proteins. By way of illustration, it can be noted that the ribosomes of E. coli (gram negative) consist of the fractions:
70 S (M: 2.7.times.10.sup.6 dalton) PA1 50 S (M: 1.8.times.10.sup.6 dalton) PA1 30 S (M: 0.91.times.10.sup.6 dalton) PA1 50 S: 34 proteins, 2RNA (23 S, 5S) PA1 30 S: 21 proteins, 1RNA (16 S).
The fractions 50 S and 30 S themselves have the following composition: